Switch-timer mechanism



Oct. 28, 1958 w. c. CRIMMINS 2,853,387

SWITCH-TIMER MECHANISM Filed 001;. 14, 1955 'PI.l

TTOR

United States Patent SWITCH-TIMER MECHANISM William C. Crimmins, Marion, Ind., assignor to Appliance Manufacturing Co., Inc., Van Buren, Ind., a corporation Application October 14, 1955, Serial No. 540,464

6 Claims. Cl. 200-38) I mount importance.

The object of my invention is an improved switch timer. A more specific object of my invention is an improved switch-timer mechanism in which a large number of simple switches are sequentially operated and are each given snap-action by a simple clock-driven mechanism.

The objects of my invention are attained by a pair of side-by-side ratchet disks with a common pawl, the one-direction ratchet teeth of the two disks being pointed in opposite directions, so that as the pawl rides up on the back ramp of one tooth of one disk, the pawl suddenly is unlatched from the front of a tooth on the other disk, a series of switches are keyed to the unlatched disk and are sequentially operated each with a snap action.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a plan view of one embodiment of my novel switch timer;

Fig. 2 is a perspective view of the ratchet disks of Fig. 1; and

Fig. 3 is a detail plan view of the cam disk 41 and wheel 40 of Fig. 2.

The switch-timer chosen for illustrating the principles of my invention, shown in Fig. 1, comprises a plurality of switch circuits including terminals 1, 2, 3, 4, et cetera, which are to be selectively and sequentially connected to terminals 11, 12, 13, 14, et cetera. Although four switches are shown, a greater or lesser number could be used without departing from my invention. The switches connected between the mentioned terminals may comprise conventional phosphor-bronze leaf spring structures such as 6, Fig. 2, with tips 7 of tungsten or other refractory metal for making and breaking with front and back contacts 4a and 4b. The leaf-spring type of switch is suggested because it is easily moved to makeand-break position by rises and valleys on simple disk cams. The switches shown are of the double-throw single-pole type with the end of the leaf spring normally in contact with either the front or back stationary contact. The cam disks 8 for operating the switches may be of the fibre-board type mounted side-by-side on the sleeve 20. One cam only is shown in Fig. 2 for clarity of illustration. The cam disks and their rises 9 rotate "ice at a fixed speed on the sleeve 20 until just before the leaf spring is to be pushed into or out of a circuit-making position. At that time, the cam is stopped by mechanism, to be described, and then, at a predetermined instant, a rotational impulse is applied to the sleeve 20 to cause the cam to jump, causing the associated switch 6 to snap into its new position.

One application for the time switch of my invention is the automatic washing machine where the washing machine motor must be stopped and started, the solenoids on hot and cold water valves, and drying circuits must be switched on-and-oif in the proper sequence.

The constant speed motor 30, such as a synchronous clock-motor, is coupled through reduction gears in housing 31 to pinion 32. Pinion 32 meshes with gear 33 to drive shaft 34 at a slow constant speed. In the washing machine application, the speed of shaft 34 may, for example, be one revolution in thirty minutes. Shaft 34 extends centrally through the mechanism and is journaled at one end in the back plate 35 and in the front plate 36 which, conveniently, comprises the supporting framework for the switch mechanisms. The front plate 36 may have stand-off legs 37 for attachment to the back side of the front panel of the machine to be controlled. The left or front end of shaft 34 receives a hand-controlled dial, not shown, properly marked to indicate the status of the electrical circuits controlled by switches 6.

It is preferred that gear 33 be coupled by a slip clutch, not shown, to the shaft 34 so that although the clock mechanism 30 will drive shaft 34 throughout a complete cycle, shaft 34 can be manually rotated. By a properly tensioned slip clutch between gear 33 and shaft 34, manual power at the dial on shaft 34 will override the constant speed drive of the clock motor and permit the advancement of shaft 34 and its connected parts to any desired point in the cycle controlled by the clock. Alternatively, the slip clutch could be incorporated in the gear train between the motor 30 and the pinion 32.

Sleeve 20 is driven by shaft 34 through an escapement mechanism, including the ratchet wheel 40 and cam disk 41, best shown in Fig. 2. Cam disk 41 is keyed to shaft 34, whereas escapement wheel 40 is keyed to sleeve 20. A yieldable spring coupling is connected between the disk and cam. In the embodiment shown in Fig. 2, the spring 42 is placed in tension between the pin 43 staked in disk 41, and the pin 44 staked in wheel 40. The tension of spring 42 is sufficient to transmit any anticipated load that may be placed on sleeve 20 by the drag of the switch-operating cams keyed to sleeve 20. Pin 43 extends through the oversize window 45 in the wheel 40 and the tension of spring 42 is sufiicient to hold pin 43 against one side of said window. In the particular mechanism shown in Fig. 2, it is contemplated that the gear 33 and disk 41 rotate in clockwise direction.

Ratchet teeth 46 are formed at uneven distances along the periphery of wheel 40, the distances being analogous, for a given clock-motor speed, to the time intervals between switching operations in the circuits of switches 6. The pawl 50 is pivoted on post 51 staked into the front panel 36 and is biased by spring 52 to scrape the edge of wheel 40. Hence, the pawl engages each tooth 46 as the tooth advances clockwise toward the pawl. It will now be observed that after Wheel 40 has been stopped by tooth 46 and pawl 50, disk 41 will continue under the driven force of the clock motor. This is accompanied by pin 43 proceeding across window 45 against the tension of spring 42. Each of the teeth 46 has been rotationally positioned on wheel 40 so that a selected one of a switch-operating cams 8 on sleeve 20 stops just short of operating its switch 6.

forward wheel-40, sleeve 20 andcams 8 in a clockwise direction and the operation of the selected switch6 is: effected. The rearvedge' of window 45 stops against pin No, furtheraswitching operations result-x until the-J1 next tooth46 is stoppedby the pawl: and-released by 7-,

the associated cam. rise 55.

Where two switching operations must be closely spaced in time and where this time is so short as measured along the periphery of wheel that two teeth 55-with separate ramps cannot be made on camdisk 41, then a singletooth 55a with .an-extra long and'higher rampmay be used, as shownin Fig. 3. Such a ramp will release the pawl from the two teeth 46 and 46a, at difierent levels, inrapid succession.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not a limitation to the scope of my invention.

The invention claimed is:

1.'A',timevcontrolled switch comprising a shaft, a dial keyed to the shaft, a clock-type motor coupled to said shaft; a sleeve telescoped over and free-running on said shaft, a cam-operated switch associated with said sleeve, two side-by-side ratchet disks centrally keyed,

respectively, to said shaft and to said sleeve, a positive 30 ing, respectively,inopposite directions; and spring cou-.

pling between the disks to yieldably hold one disk at one backlash position with respect to the other disk.

2. A swftch'timer'comprising a first rotatable shaft, a constant speed motor driving said first shaft, a second rotatable shaft, a plurality of circuit closers responsive to said second shaft at different rotational positions thereof, yieldable coupling means between said shafts, means for stopping rotation of said second shaft just short of each of said different rotational positions, and means responsive to said first shaft for suddenly releasing the stoppingjmeans at predetermined intervals of time.

3; In the switch timer defined in claim 2, said yieldable coupling means comprising a spring under stress connected between lever arms respectively on said first and second shafts 4. In the switch timer defined in claim 2, said means for stopping the second shaft comprising a ratchet wheel keyed to said second shaft and with teeth at positions corresponding to the mentioned second-shaft positions, and a stationary-pawl for engaging said teeth.

5. In the switch timer-defined in claim 4, said releasing means comprising a cam with irregularly spaced rises,wsaid pawl being responsive to said rises to disengage the teeth of said ratchet wheel.

6. In the 'switch'timer :defined in claim 2, said releasing meansv comprising an escapement pawl and ratchet References Cited in the file of this patent UNITED STATES PATENTS 1,760,547" Fisher May 27, 1930 1,831,605' Porter Nov. 10, 1931 2,753,406 Pigman July 3, 1956 FOREIGN PATENTS 710,027- GreatvBritain June 2, 1954 

